Purpose:
SUSAC syndrome is a very rare occurring microangiopathy of the central nerval system concerning retinal, cochlear and cerebral vessels. Pathophysiology remains unclear. In this study, electroretinographic and angiographic changes were investigated.
Methods:
Visual acuity, visual field tests (frequency doubleing perimetry, Goldmann perimetry, microperimetry), visual evoked potentials (VEP), electroretinography (ERG), fundus autofluorescence (FAF), optical coherence tomography (OCT) and angiography with both, fluorescein (FLA) and indocyanine green (ICG), dyes were examined in 13 patients with assured diagnosis of SUSAC syndrome at the SUSAC Center Muenster, Germany.
Results:
Visual acuity was 20/20 in all patients, but visual field defects were seen in 10 out of 13 patients. The patients without visual field defects (Goldmann perimetry) had significantly more hearing loss than the other patients. Fundus autofluorescence showed peripheral areas of non-perfusion in most patients. Eight patients showed a reduction in either retinal nerve fiber layer thickness (RNFLT) or total macular volume (TMV) on OCT. In fluorescein angiography, typical signs of SUSAC syndrome were seen: branch retinal artery occlusions (BRAO), arterial wall hyperfluorescence, and retinal arterial wall plaques. Indocyanine green angiography was normal in most patients, but showed scattered punctual peripheral hyperfluorescences in those patients who did not have visual field defects. The ERG findings showed reduced amplitudes of a- and b- waves and of the postreceptoral answers in general. The multifocal ERG showed almost normal amplitudes foveolar which were significantly reduced in the periphery. VEP revealed normal latencies with subnormal potentials in most patients.
Conclusions:
Electrophysiological and ICG findings give additional information about the initiation and progression of SUSAC syndrome. They can be very helpful in the diagnosis of untypical cases of SUSAC syndrome (i.e. patients without visual field defects). Therefore, we recommend those as valuable tools to diagnose SUSAC syndrome.
Keywords: electroretinography: clinical • ischemia • visual fields